Ed25519 signatures are elliptic-curve signatures, carefully engineered at several levels of design and implementation to achieve very high speeds without compromising security.

This system has a 2¹²⁸ security target; breaking it has similar difficulty to breaking NIST P-256, RSA with ~3000-bit keys, strong 128-bit block ciphers, etc. The best attacks known actually cost more than 2¹⁴⁰ bit operations on average, and degrade quadratically in success probability as the number of bit operations drops.

My two cents on usability

As in JavaScript client applications we usually tend to deal with base64 encoded keys and raw String messages, I decided contribute with an NPM package that abstracts the Uint8Array arrays manipulations: nacl-signature